Add sys exit instead of raising AssertionError

install.py

@@ -7,6 +7,7 @@ Inspired by https://github.com/dmerejkowsky/dotfiles
 
 import argparse
 import subprocess
+import sys
 from typing import List, Optional
 from urllib.request import urlretrieve
 
@@ -38,15 +39,18 @@ class Installer:
 
     def verify_secrets(self) -> None:
         """The repository contains a secrets.template, that must be taken care of
-        by the user. If the secrets is wrong, fail.
+        by the user. If the secrets is wrong, or missing, fail.
         """
 
         try:
             with open("secrets", "r") as secrets_file:
                 secrets = secrets_file.read()
-                # TODO: check the contents too
         except FileNotFoundError:
-            raise AssertionError("Did you forget to create a 'secrets' file?")
+            print("No 'secrets' file found. Did you forget to create it?")
+            sys.exit(1)
+        else:
+            pass
+            # TODO: check the contents of the file
 
     def define_os(self) -> str:
         """Define what OS we are using."""